Ladder accidents are some of the most preventable in the building and construction industry. There have been a number of devices developed to prevent ladders from being displaced from their setting during use. Many of these attach to the sides of the ladder and provide lateral support. These devices are usually attached to the lower portion of the ladder rails and do not prevent slippage or bending due to weight bearing. Such lateral stabilizers are taught in U.S. Pat. Nos. 6,167,989; 4,147,231; 4,519,477; and 5,423,397.
A European Patent discloses a stabilizer for an extension ladder having laterally extendable side legs of fixed length that are attached to the upper end of the lower segment of an extension ladder with brackets affixed to the outside of the rails. The brackets are U-shaped and have a series of holes permitting the legs to be set at several points along the brackets. Lower braces are also fixed at one end to the ladder using U-shaped brackets that enable the braces to pivot and at the other end to the lower portion of each leg. This system provides only lateral support. (App. No. 84305669.8 to Ralston)
In U.S. Pat. No. 2,574,286, Rein teaches a ladder brace consisting of two backward facing horizontal struts, one end of each being bolted to the inside of the lower ends of each of the rails. The other end of each strut is pivotally connected to a longer support strut with slots along its upper end and a pivoted shoe at the bottom. The slots can be set by cooperation with the lowest rung of the ladder. The slot chosen determines the angle of lean of the ladder which may not conform to present safety standards. This system is not practical with long extension ladders. The supports of Rein are also situated too low on the ladder to provide real stability or to prevent any weight bearing distortion.
Hawkins, in U.S. Pat. No. 4,565,262, teaches a ladder assembly and stabilizer that can be added to an extension ladder using two posts passing through two of the hollow rungs. The upper post is placed near the top of the lower segment of the extension ladder and the lower post is placed near the midpoint of the lower segment. A leg is affixed to each side of the upper post in such a manner that the legs can extend laterally and to the back of the ladder. One of end of a telescoping strut is pivotally attached to each end of the lower post with its other end attached to the approximate midpoint of a leg by means of a hook. There are two cross struts or braces, also telescoping, attached at one end near the top of each leg and at the other end to the midpoint of the leg using the same hook. Each leg can be set at a different angle and the assembly can fold against the ladder rails for storage. Extensions at the end of each leg can be adjusted for uneven terrain. The hook connectors, though enabling a three-point connection, are open and do not appear sufficient to hold the system together under the stress of repeated use.
A ladder stabilizer for step ladders is described by Stewart in U.S. Pat. No. 4,964,488. Brackets are attached to the ladder rails at a point just below the foldable support strut of the ladder and at a point just below the bottom rung on each rail. A leg is attached to each upper bracket by hinges and a brace is similarly attached at one end to a lower bracket and at the other end to a leg. Neither the legs or the braces are adjustable. The hinges permit the legs to swing about an arc of 230° from the plane of the rails around to the front of the opposing rail. The legs cannot extend behind the ladder and appear to provide lateral support only.
Murrell discloses a safety extension ladder having ratcheted extendable legs for adjustment due to uneven terrain and a support system attached to the lower end of the first segment of the ladder. The support system is made up of outriggers having an upper leg and a lower leg that meet at a pivoted foot. The upper leg is pivotally attached below the midpoint of the lower segment of the ladder by means of a bracket bolted to the rail, and the lower leg is pivotally attached to a frame at the bottom of the ladder. The outriggers can rest on the ground at a range of angles as well as to the side and behind the ladder and can also be raised above the ground to support the ladder against a vertical surface. They fold for storage. The outriggers are not adjustable in length and are permanently attached to the ladder and fixed at its lower end. (U.S. Pat. No. 4,632,220)
The ladder stabilizer of Levi et al. as disclosed in U.S. Pat. No. 4,899,849 supports an extension ladder using two height adjustable legs set into U-shaped brackets attached to the outside of the upper end of each rail of the lower segment of the ladder. The brackets fix the angles of the legs at 45° back from the plane of the ladder rails. A brace on each side extends from about the midpoint of each rail to a leg. Neither the angle nor the lengths of the braces are adjustable, thus fixing the angle of incline of the ladder. The braces are located at too high a level to prevent the ladder from sliding backward from the vertical support structure. In a subsequent patent Levi et al. uses side braces attached near the bottom of the rails and a ratcheted leg extension that can be securely set in place to fix the length of the legs. The side braces are foldable but not length adjustable. (U.S. Pat. No. 4,949,809)
Hrincu uses a pivot bar passed through a hollow rung at about the midpoint of a straight non-extendable ladder. Brackets on each side of the pivot bar hold adjustable length legs that provide the support. Crossed struts further enforce the legs. Cords or wires prevent the legs from extending more than a fixed distance back from the ladder. This system appears to be very flimsy and the legs cannot move laterally. (U.S. Pat. No. 6,527,084)
All of the ladder stabilizers that are attached to the ladder by means of brackets bolted to the side rails require the drilling of holes into the rails to attach the brackets. These holes can weaken the rails and damage the integrity of the ladder thereby interfering with the manufacturer's requirements to comply with statutory safety specifications.
There is a need for a ladder stabilizing assembly for extension ladders that is fully adjustable both in the legs and the braces and one that does not require drilling holes into the rails. There is a need for a ladder stabilizing assembly that can be set at the proper angle for safety and can provide support for heavy loads that would cause an unsupported ladder to bend or distort. There is a need for a ladder stabilizing assembly that makes the ladder sufficiently stabile and tip proof so as to enable the user to wear a safety harness while working on the ladder.